68 PRINCIPLES OP PLANT-TEEATOLOGT. 



original condition, and this is sometimes accompanied 

 by the reappearance of the median posterior sepal in 

 order to lie opposite the gap so formed. 



The morphological importance of this division of the 

 posterior petal is not affected, as Camus thinks it to be, 

 by the fact, observed by him in four species, that the 

 anterior petal divides still more frequently, for it is a 

 not infrequent phenomenon in Dicotyledonous flowers 

 for the number of petals to be increased by one or two 

 members. Camus also saw 5-merous flowers due to 

 bipartition of one of the lateral petals, 6-merous flowers 

 due to dedoublement of both the anterior and posterior 



/ 



Fio. 87. — Fuchsia. Toung flower-bud showing petal-rudiments (p) 

 dividing collaterally. (After Goebel.) 



petals, and, finallj', 6- and 7-merous ones due to tripling 

 of the anterior petal. 



In the majority of grasses only the two anterior 

 "lodicules" (representing, according to most botanists, 

 vestigial petals) are present, the posterior one having 

 disappeared owing to the fusion of the two posterior 

 sepals into a single medianly-placed sepal. Schacht 

 observed, in tlie development of Agrupyrnm giganteinn 

 {Triticwin rigidiini), in which the two posterior sepals 

 were separated, the presence of the third posterior 

 " lodicule." In two of the more ancient types of 

 grasses, StreptocJiseta, and some species of bamboo, three 

 "lodicules" are normally present. 



In "double" flowers the increased number of petals 



